1. Field of the Invention
The present invention relates to a method for producing a light guide plate mold having V-shaped grooves by photolithography, the mold being used for forming light guide plates installed into LCD (liquid crystal display) devices.
2. Description of the Prior Art
Nowadays, backlight units (BLUs) are generally used as light sources of thin film transistor liquid crystal display (TFT-LCD) modules. The function of the BLU is to emit light beams into a display panel of the TFT-LCD module, so as to make the intensity of transmitted light beams as high and as uniform as possible. In order to help achieve this goal, a light guide plate is employed in the BLU. The light guide plate is an important component in the BLU, and is usually made of polymethyl methacrylate (PMMA).
Currently, injection molding is a typical method for mass producing light guide plates. A light guide plate mold is needed for injection molding. The light guide plate mold enables each formed light guide plate to have a micro-optical pattern, such as V-shaped grooves. The micro-optical pattern enables the light guide plate to transmit light beams with high uniformity and brightness.
The light guide plate mold has a predetermined micro-optical pattern therein. In the process of fabrication of the light guide plate, the micro-optical pattern is transferred onto a surface of the light guide plate.
Conventionally, the micro-optical pattern of the light guide plate mold is fabricated by precision machining technology. Micro-scale diamond cutting tools directly score a plurality of V-shaped grooves on a surface of a light guide plate mold substrate. Even though this manufacturing method is simple, it has two notable disadvantages. First, the machine used in the process is very expensive, making the cost of producing the light guide plate mold unduly high. Second, line defects or point defects in the micro-optical pattern are common, thereby reducing the precision of the V-shaped grooves.
Therefore, it is desired to provide a new method for producing a light guide plate mold with V-shaped grooves which overcomes the above-described disadvantages of conventional processes.